The fundus hemorrhage requiring surgery mentioned here refers to vitreous hemorrhage. diabetic retinopathy has progressed to the proliferative stage, and small hemorrhages on the retinal surface in the non-proliferative stage are not under discussion. The so-called proliferative diabetic retinopathy is generally referred to as diabetic retinopathy stage 4-6. stage 4 is when the retina starts to grow neovascularization, which is a compensatory response to retinal ischemia, but the neovascularization is very unhealthy and prone to rupture and bleeding. stage 5 is when the retinal neovascularization mechanizes to form a fibrovascular membrane. stage 6 is when the fibrovascular membrane contracts and pulls the retina, causing retinal detachment. In general, if vitreous hemorrhage is not absorbed for more than 1 month at stage 4, vitrectomy can be considered as early as possible; if the hemorrhage is not absorbed for more than 3 months, early surgery should be performed; otherwise, the neovascularization will easily mechanize and form fibrovascular membrane, which will not only not absorb the hemorrhage, but also greatly increase the difficulty of future surgery. In some cases, the bleeding is quickly absorbed, but after some time there is bleeding again, and so on repeatedly. At this time, supplementary treatment with fundus laser can be considered in the interval of bleeding absorption, and if it does not work, then surgery should also be considered. In stage 5 and 6 patients with proliferative membrane not involving the macula and no or very little vitreous hemorrhage, laser treatment can be considered first, and those who cannot be controlled should be operated in time.